Centrifugal photometric analyzer

ABSTRACT

A centrifugal photometric analyser comprises a rotor having a plurality of cuvettes at least some of which have inlets opening at different axial levels of a central feed region of the rotor, and feed means opening with a radially outwards component at said axial levels so that the cuvettes can be supplied with different material at the different axial levels.

United States Patent [191 Molloy et al. v

[ Nov. 13, 1973 {7 1 Assignee: MSLE. Holdings llirnited, Sussex,

[ CENTRIFUGAL PHOTOMETRIC ANALYZER [75] Inventors: James Oscar Molloy, Surrey; Peter Dunnill, London; Malcom Douglas Lilly, Kent, all of England England [22] Filed; Mar. 24, 1971 21 Appl. No.: 127,731

[ 30] rorig'lfxppneanon Priority Data Mar. 25, 1970 Great Britain ..l4607/70 [52] U.S. Cl 356/197, 356/246, 233/26 [51] Int. Cl. G0ln 21/24 [58] Field of Search. 233/1 R, 26, 46,

233/47 R, l3, 14 R, 27, 28,15,19 R;

[56] References Cited UNITED STATES PATENTS 1,011,077 l2/l9ll Peck 233/19 R 2,036,924 4/1936 Coutor 233/15 3,586,484 6/1971 Anderson 233/1 R 2,622,796 12/1952 Steinacker et al. 233/19 R 2,956,434 10/1960 Donoghue 233/27 X 2,173,580 9/1939 Fawcett 233/27 X 3,326,459 6/1967 3,547,547 12/1970 Anderson 356/197 Primary Examiner-George H. Krizmanich Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT I A centrifugal photometric analyser comprises a rotor having a plurality of cuvettes at least some of which have inlets opening at different axial levels of a central feed region of the rotor, and feed means opening with a radially outwards component at said axial levels so that the cuvettes can be supplied with different material at the different axial levels.

16 Claims, 9 Drawing Figures SHEET 3 BF 4 PATENTEDHUV13 1975 PATENTEDNuv 13 ms SHEET 0F 4 FIGS FIG.9

1 CENTRIFUGAL PHOTOMETRIC ANALYZER BACKGROUND OF THE INVENTION This invention relates to centrifuging apparatus and concerns such apparatus in the form of a centrifugal photometric analyser having a rotor containing a plurality of sample analysis chambers, called cuvettes, having wall portions which are transmissive to a predetermined radiation, so that, during centrifugation, that radiation can be passed through samples in the cuvettes.

In such analysers, the cuvettes are 'all loaded at the same axial level with liquid from concentric sets of liquid-holding cavities in a disc manually disposed at the centre of the rotor at the beginning of an analysis. Such a disc is needed especially when the cuvettes are to be loaded with different samples to be analysed simultaneously. However, to commence a further analysis, clearly the rotor must be stopped, washed and the disc manually reloaded.

It is an object of the present invention to provide a rotor for such an analyser in which cuvettes may be individually loaded with different items, such as reagent, sample and washing fluid, during uninterrupted rotation of the rotor and may be re-loaded without stopping the rotor.

SUMMARY OF THE INVENTION According to the present invention, there is provided a cuvette rotor for a centrifugal analyser said rotor defining: r I

' a central rotor feed region by way of which different liquids can be simultaneously fed to the rotor at distinct, respective, axial levels of said region;

a plurality of cuvettes disposed within respective segmental regions of the rotor so as to be angularly spaced from one another, the cuvettes having wall portions transmissive to a certain radiation;

inlets to said cuvettes at said distinct axial levels such that each of said cuvettes has its inlet at an axial level which is different from the axial level of the inlet of at least one other of said cuvettes; and out- I lets of said cuvettes. 1 I

In one embodiment, the cuvettes have inlets at respective levels. A preferred form provides a rotor component having one cuvette, a rotor being formed by stacking two or more of such components. In the general case, the rotor includes at least two groups of cuvettes fed from respective ones of at least two axial levels, it being understood that each group may consist of one or more cuvettes. When a group has more than one cuvette, fluid may be distributed between the cuvettes of the group by dynamic stream segmentation. By dynamic stream segmentation, we mean the substantially uniform distribution of fluid'to a plurality of cuvettes which can be achieved by directing a single stream of fluid outwards on a substantially fixed path with a radial component from said central region of the rotating rotor towards radially inwardly facing cuvette inlets. In addition or alternatively to such a feed, one may have means for providing a rotating stream to the inlets, possibly by way of a rotating face seal. Preferably, the cuvettes of the at least two groups are axially substantially co-extensive. Of course, more than two groups may be provided, with inlets at respective axial levels.

In one construction of rotor for a chemical analyser, the rotor comprises a plurality of rotor portions in an axial succession, each portion defining at least one group of cuvettes, the cuvette or cuvettes of each group being staggered angularly from those of each other group and the rotor portions being apertured so that radiation can be passed through the cuvettes via all the rotor portions. One or more of the rotor portions may be integral with others of the rotor portions.

In use, a first fluid inlet pipe or pipes may have an outlet or outlets at a first axial level of the feed region and a second such pipe or pipes may open at a second axial level, the pipes being stationary so that, for'exam ple, different reactions can be carried out simulta neously in the respective groups; the groups can thereafter be emptied, further reactions carried out, and so on without stopping the rotor.

DESCRIPTION OF DRAWINGS ence will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 is a diagrammatic, partially sectioned, partially cut-away view of a centrifugal photometric analyser; 1

FIG. 2 is a perspective view of a part of the rotor of the analyser of FIG. 1;

FIG. 3 is a cross-section of the rotor of the analyser of FIG. 1; I

FIG. 4 is a partially cut-away perspective view of an alternative form of a rotor component for a chemical analyser;

FIG. 5 is a section of the component of FIG. 4 on the line AA, and showing associated closure discs and fixed feed tubes;

FIG. 6 is a diametral section of a modified form of the component of FIG. 4;

FIG. 7 is a plan view of a further embodiment of an analyser rotor;

FIG. 8 is a cross-section on the line AA of the rotor of FIG. 7; and

FIG. 9 shows another embodiment of rotor in axial section.

DESCRIPTION OF EMBODIMENTS The embodiments illustrated relate to a chemical centrifugal photometric analyser having a rotor containing a plurality of cuvettes or chambers into which samples, reagents and other liquids are fed by centrifugal action, the cuvettes having transparent axial end walls so that the contents of the cuvettes may be subjected to radiation, e.g., for absorption measurements.

FIG. 1 is a diagrammatic view of such an analyser. A rotor l is mounted in a temperature-controlled housing 2 and is coupled to a drive motor 3. The rotor 1 comprises a circular aluminium housing 4 having an annular lid 5, both containing apertures 6 for the passage through the rotor of light from a light source 7 to a photomultiplier 8 connected to a digital computer 9. The housing 4 contains a number of discs defining a plurality, in the present example two, of cuvettes 10 which are sample containers with transparent axial end walls aligned with respective opposed pairs of the apertures 6.

The lower surface of the housing 4 carries a circular series of magnets 11 corresponding to respective cuvettes, these magnets being detected by a detector 12 which delivers to the computer a series of pulses defining the moments at which the photomultiplier output corresponds to light transmitted through a cuvette. An additional magnet 13, angularly displaced from magnets 11, is detected by a detector 14 which supplies a pulse to the computer to define a predetermined angular position of the rotor, from which the computer can determine which of the cuvettes is being sensed at any particular moment.

Associated with the rotor 1 is a set of feed tubes 15 carried by a plate 150 held against rotation but urged against a bearing gasket 16 by springs 17. Two feed tubes 15, one for each cuvette, are shown for simplicity, but in practice each cuvette will be associated with a plurality of feed tubes, one for each component to be fed to a cuvette. A vacuum line 18 is also coupled to the plate 15a.

Outlets of the cuvettes are provided by annular channels 19 in the housing 49 and stainless-steel tubes 20 which are a force fit in passages opening into the channels. The stainless-steel tubes open into an annular collecting channel 21.

The feed tubes 15 are supplied with metered quantities of substances, e.g., reagent, sample, and water, from a rotary valve 22 supplied with the substances via tubes 23, the substances normally passing to waste or for recirculation through the valve via outlet tubes 24. A rotary portion 25 of the valve contains metering passages 26 maintained full by the flow fromtubes 23 to 24. On angularly displacing the portion 25 by actuator 27, the metering passages are put into communication with the feed tubes 15 and their metered contents are delivered into the feed tubes 15 by compressed air supplied by tubes 28. Compressed aircan also be delivered to the central region of the rotor, by the tube 18 or another such tube, to discharge the cuvette contents.

Considering the rotor construction again, it comprises in this embodiment five discs 29, 30, 31, 32 and 33, the lower four of which are shown in the perspective view of FIG. 2. The five discs are shown in the cross-sectional view of the rotor given in FIG. 3.

The discs 29, 31 and 33 are transparent discs, the discs 29 and 31 having central circular apertures 34 defining a central feed region into which the feed tubes 15 extend. The disc 31 divides the feed region into two, axially displaced, feed levels 35 and 36, one group of the feed tubes 15 opening at one of the levels and another group at the other level.

The discs and 32 are identical, opaque, discs each having a circular aperture 37 eccentrically formed. At the point of the aperture 37 most remote from the rotor axis the aperture periphery has a slot 38 providing an inlet to a cuvette 10.

Thus, liquid discharged by a feed tube 15 at the level of aperture 37 and with an outwards component, will contact the wall of the aperture 37 and'be constrained, during rotor rotation, to flow along that wall to slot 38 and thus into the associated cuvette. The disc 31 will prevent the liquid passing to the cuvette at the other axial level. p

A cuvette outlet is provided by a slot 39 in one major surface of the disc 30 or 32, this slot acting as a syphon.

Each of discs 30 and 32 also has an aperture 40 diametrically opposite, and on the same radius as, cuvette 10. Diametrically opposite apertures 41 are angularly displaced from aperture 40 and cuvette 10, so that light can be passed through the rotor independently of the cuvette contents to provide, as a reference, a measure of the transmission properties of the rotor itself.

The discs 30 and 32 are offset from one another by so that the cuvettes 10 are diametrically opposite in the completed rotor, whilst each cuvette lies on an optical path through the aperture 40 in the other of the discs 30 and 32.

A plurality of discs, such as discs 30 and 32, could be stacked in this manner with intervening discs 31. When such a facility is required, each disc 30, 32 will have an appropriate number of other apertures 42 (shown dotted)corresponding in function to aperture 40.

As there are a plurality of feed tubes 15 associated with each axial feed level, each of these tubes can have a distinct function and can be used simultaneously with and independently of the others. Thus, one tube can be used to introduce a sample and another or others a reagent or reagents into one cuvette via one axial feed level. Moreover, the tubes associated with the other cuvette can be used to produce reactions in that other cuvette simultaneously with and independently of reactions in the one cuvette. Furthermore, feed tubes can be used for washing the cuvettes after reactions, all these described functions occurring without interrupting the rotation.

Other functions may also be carried out without interrupting the rotation. For example, the cuvettes can be discharged through the syphons 39, the discharge being initiated by the washing liquid and/or by positive pressure at the rotor centre find being completed by syphon action in the syphons 39 (in an alternative embodiment suction at the rotor periphery might be employed). In addition, mixing can be accomplished by creating suction at the centre of the rotor by way of tube 18 to drive gas bubbles through the cuvettes (in an alternative gas pressure is created at the periphery).

In summary, the described rotor permits of different simultaneous reactions, as well as successive reactions, in the cuvettes without stopping the rotor.

FIG. 4 shows an alternative form of annular disc 30 or 32 for the rotor of aphotometric analyser. The rotor in this case is completed by clamping the disc between two transparent annular discs 29 and 31, as shown in the cross-section of FIG. 5. Means will also be provided to secure the rotor to a motor drive, as in the case of FIGS. 1 to 3.

The disc of FIG. 4 contains eight cuvettes, a first group of four cuvettes 43 and a second group of four cuvettes 44. The axial ends of these cuvettes are closed by the discs 29 and 31.

The radially inner sides of the cuvettes communicate with the central open region of the disc via passages 45 which converge towards the cuvettes. The passages form two axially offset groups associated with respective ones of the two groups of the cuvettes and are separated by a septum 46.

The radially outer sides of the cuvettes communicate with the disc periphery via capillaries or syphons 39 which have a reverse bend 47, as in the preceding embodiment, defining the maximum volume which can be contained in the cuvettes under centrifugal force. The dotted line 48 indicates the approximate surface level in a cuvette as determined by the associated capillary.

In use, the rotor described is associated with a plurality of feed tubes 15 (FIG. 5) some of which open at a first axial level above the septum 46 and others of which open at a second axial level below the septum. Each tube opens radially outwardly and towards the cuvettes. If liquid is passed through one of the tubes, it emerges as a radial stream which is distributed substantially uniformly between the cuvettes of the associated group with a constant rotor speed. This action is what we refer to as dynamic stream segmentation. It is to be noted especially that this action arises in this embodiment because the passages 45 cut each other at corners 55 at their inner ends and the adjacent pairs of corners 55 subtend equal angles at the rotor axis, so that the stream of liquid will be appropriately directed to the cuvettes and apportioned equally between them.

As has already been indicated, the rotor can be designed to provide more than two cuvettes, or groups of cuvettes, with access at respective, distinct, axial levels so that three or more cuvettes, or groups of cuvettes, can be used simultaneously and independently. This can be achieved by stacking rotor discs, such as the discs 30 and 32 of FIG. 2 or the disc such as that of FIG. 4. An alternative development is shown in FIG. 6 which is a diametral section of a rotor disc formed of a single piece of material, for example by the use of a core mould having a plurality of discs of a material, e.g., aluminium, which will be removed chemically after moulding. This disc provides eight axial levels, at each of which entry is made to a cuvette in the manner of FIG. 2 or to four cuvettes in the manner of FIG. 4. All the cuvettes are axially coextensive and each is angularly spaced from the others.

Because of the additional axial height of the cuvettes created by the axially coextensive arrangement, each cuvette may have two capillaries or syphons, one at each axial end, together with an air vent capillary which extends from the periphery of the disc and opens at a region of the cuvette outside its region defined by capillaries or syphons to contain liquid. Such a vent will assist in the removal of bubbles from the liquid during centrifuging and dissipate air locks.

The rotor discs of FIGS. 4 and 6 can also be constructed of separate layers secured together with the or each septum formed by a sandwiched transparent disc in the manner of disc 31 of FIGS. 2 and 3; for example the disc of FIG. 4 can suitably be formed from a stack of three discs.

FIGS. 7 and 8 show a plan view and section on A-A of a rotor having eight cuvette groups and constructed of a stack of four discs 49 each as shown in FIG. 4. These discs are separated and sandwiched by transparent annular discs 50. Each disc 49 contains not only its eight cuvettes but also other apertures 40 which define light paths for the cuvettes of other discs. As illustrated in FIG. 7 at least some of the apertures 40 may be merged into a single aperture 51.

In FIGS. 6 and 8, the feed tubes 15 are not illustrated but it will be appreciated that these tubes singly and/or in groups will open radially at the respective axial cuvette inlet levels.

FIG. 9 shows another form of rotor in axial nondiametral section such as A-A taken in FIG. 7. This rotor comprises an outer annular rotor section 52 defining a plurality of cuvettes 10, in this example 16 in four groups of four, which open at the inner periphery of the section. An inner rotor section 53 defines four distinct axial inlet levels to the respective groups of cuvettes. At each axial level there are four inlet passages 54 converging radially towards the cuvettes and of the form generally as shown in FIG. 4. Moreover, the inner rotor section itself converges towards the outer rotor section, i.e., the passages associated with the respective groups converge as seen in the axial plane. Consequently, the cuvettes are axially coextensive, yet their axial extent is less than the combined axial extent of the axial inlet levels.

As in the previous embodiments, feed tubes will be provided for discharge of fluid to the cuvettes at respective levels, as will drainage syphons.

In addition, the two rotor sections could be formed as one part, or the rotor could be separable into parts, alternatively o'r'additionally to the illustrated separation, at some other region of the rotor.

We claim:

1. A cuvette rotor for a centrifugal analyser, said rotor defining:

a central rotor feed region by way of which liquids can be fed to the rotor;

a plurality of cuvettes disposed within respective segmetal regions of the rotor so that the cuvettes are angularly spaced from one another, said cuvettes having wall portions transmissive to a certain radiation;

inlets to said cuvettes, the inlets opening into the central feed region at distinct axial levels of the rotor such that each of said cuvettes has its inlet opening into the central feed region at an axial level which is different from the axial level at the central feed region of the inlet of at least one other of said cuvettes; and

outlets ofv said cuvettes.

2. A rotor as claimed in claim 1, and comprising a group of more than one of said plurality of cuvettes having inlets all of which open at one axial level of the central feed region, each of the inlets of the group diverging towards the central feed region with adjacent ones of the inlets of the group meeting at a cusp to provide for dynamic stream segmentation of liquid from said central region to said inlets of said cuvettes of said group.

3. A rotor as claimed in claim 1, wherein said rotor is formed by a plurality of stacked components comprising: at least one first component defining side wall portions of said cuvettes;v and, at the axial sides of said at least one first component, second components defining said transmissive wall portions.

4. A rotor as claimed in claim 3, and comprising at least two first components each in the form of a member having an eccentric aperture at an associated one of said axial levels, a second aperture defining said side wall portions of one of said cuvettes, an opening providing communication to said one cuvette from that region of said eccentric aperture which is most remote from the axis of said rotor and a channel defining said outlet of said cuvette.

5. A rotor as claimed in claim 4, in association with feed tubes opening with an outward radial component at said distinct axial levels.

6. A rotor as claimed in claim 3, wherein said at least one of said components has a central aperture defining a part of said central rotor feed region, a septum dividing said central aperture into two distinct axially spaced feed levels, at least two axially coextensive apertures defined by said side wall portions ofat least two respective cuvettes, an inlet to one of said at least two cuvettes communicating with one of said feed levels, an

inlet to another of said at least two cuvettes communicating with the other of said feed levels, and channels defining said outlets of said at least two cuvettes.

7. A rotor as claimed in claim 6, in association with feed tubes opening with an outward radial component at said distinct axial levels.

8. A rotor as claimed in claim 6, wherein said one component defines more than two axial feed levels and associated cuvettes.

9. A rotor as claimed in claim 8, wherein said one component is a monolithic part.

10. A rotor as claimed in claim 8, wherein said one component is in two parts, one defining said side wall portions of cuvettes and the other, disposed in a central region of said one part, defining said inlets and associated septa and feed levels.

1 1. A rotor as claimed in claim 10, wherein said other part is of greater axial height than said one part and converges, in an axial plane, towards said one part.

12. A rotor as claimed in claim 1, wherein at least two of said cuvettes have different axial feed levels yet are axially coextensive.

13. A rotor as claimed in claim 1, wherein said outlets are syphons.

14. A rotor as claimed in claim 1, wherein said rotor comprises a support, having peripheral outlet passages communicating with said outlets, and tubes extending from said outlet passages and overhanging the support.

15. A rotor as claimed in claim 1 in association with feed tubes opening with an outward radial component at said distinct axial levels.

16. A rotor as claimed in claim 14, including a centrifugal photometric analyser means operatively associated therewith. 

1. A cuvette rotor for a centrifugal analyser, said rotor defining: a central rotor feed region by way of which liquids can be fed to the rotor; a plurality of cuvettes disposed within respective segmetal regions of the rotor so that the cuvettes are angularly spaced from one another, said cuvettes having wall portions transmissive to a certain radiation; inlets to said cuvettes, the inlets opening into the central feed region at distinct axial levels of the rotor such that each of said cuvettes has its inlet opening into the central feed region at an axial level which is different from the axial level at the central feed region of the inlet of at least one other of said cuvettes; and outlets of said cuvettes.
 2. A rotor as claimed in claim 1, and comprising a group of more than one of said plurality of cuvettes having inlets all of which open at one axial level of the central feed region, each of the inlets of the group diverging towards the central feed region with adjacent ones of the inlets of the group meeting at a cusp to provide for dynamic stream segmentation of liquid from said central region to said inlets of said cuvettes of said group.
 3. A rotor as claimed in claim 1, wherein said rotor is formed by a plurality of stacked components comprising: at least one first component defining side waLl portions of said cuvettes; and, at the axial sides of said at least one first component, second components defining said transmissive wall portions.
 4. A rotor as claimed in claim 3, and comprising at least two first components each in the form of a member having an eccentric aperture at an associated one of said axial levels, a second aperture defining said side wall portions of one of said cuvettes, an opening providing communication to said one cuvette from that region of said eccentric aperture which is most remote from the axis of said rotor and a channel defining said outlet of said cuvette.
 5. A rotor as claimed in claim 4, in association with feed tubes opening with an outward radial component at said distinct axial levels.
 6. A rotor as claimed in claim 3, wherein said at least one of said components has a central aperture defining a part of said central rotor feed region, a septum dividing said central aperture into two distinct axially spaced feed levels, at least two axially coextensive apertures defined by said side wall portions of at least two respective cuvettes, an inlet to one of said at least two cuvettes communicating with one of said feed levels, an inlet to another of said at least two cuvettes communicating with the other of said feed levels, and channels defining said outlets of said at least two cuvettes.
 7. A rotor as claimed in claim 6, in association with feed tubes opening with an outward radial component at said distinct axial levels.
 8. A rotor as claimed in claim 6, wherein said one component defines more than two axial feed levels and associated cuvettes.
 9. A rotor as claimed in claim 8, wherein said one component is a monolithic part.
 10. A rotor as claimed in claim 8, wherein said one component is in two parts, one defining said side wall portions of cuvettes and the other, disposed in a central region of said one part, defining said inlets and associated septa and feed levels.
 11. A rotor as claimed in claim 10, wherein said other part is of greater axial height than said one part and converges, in an axial plane, towards said one part.
 12. A rotor as claimed in claim 1, wherein at least two of said cuvettes have different axial feed levels yet are axially coextensive.
 13. A rotor as claimed in claim 1, wherein said outlets are syphons.
 14. A rotor as claimed in claim 1, wherein said rotor comprises a support, having peripheral outlet passages communicating with said outlets, and tubes extending from said outlet passages and overhanging the support.
 15. A rotor as claimed in claim 1 in association with feed tubes opening with an outward radial component at said distinct axial levels.
 16. A rotor as claimed in claim 14, including a centrifugal photometric analyser means operatively associated therewith. 